Nightmare on Floor 17

As Josh arrived at the Tower plaza, he couldn't help but smile, seeing how spacious it was. There were no more stalkers that— never mind. Actually, there were still a few.

They were now ogling him and the way too many spears he was carrying. Can't a man bring a few dozen spears on a casual walk in the Tower! Anyway, he happily teleported in. 

His first thought upon seeing the interior was 'beach episode', for he could feel the soft sand under his feet. But, the surroundings were pretty bare and consisted mostly of an empty track surrounded by very tall dark brick walls. 

[Mission: Summon The Prime Nightmare!] 

"So, what's this about? Prime Nightmare, eh? Let me try this….2,3,5,7,11,13 ….so how many do I have to list for the nightmarish version to appear?" But only silence answered him.